Non-rechargeable, or zinc-air batteries, come in a variety of sizes, depending upon the model of hearing aid. The most common sizes are:
10, which is the smallest battery available, usually used for small, completely-in-the-canal hearing aids, will last 3-5 days.*
312, which is the next size up and is the most commonly used size, will last 5-7 days.*
13, the next size larger, used for larger hearing aids, will last 7-10 days.*
*Note that these are approximate useful life estimates, as battery life will ultimately depend upon the number of hours used per day, the programming levels of the individual hearing aid, whether the aids are turned off when not in use, and whether the aids are used for streaming phone calls, TV, or computers.
Please note also, that batteries have a limited shelf life. Be sure to check the expiration date on the package before you purchase them to be certain they will last until you need to use them.